The Jimi Hendrix movie “All Is by My Side” had to be re-edited after the guitar god’s ex-girlfriend complained to the Irish Film Board, which subsidized the film.

Kathy Etchingham discovered Hendrix in London in 1966 before he was famous, and dated him for three years. She tells Page Six the film is “ridiculous . . . sexist’’ and “dull as dishwater.” The movie by John Ridley (who wrote the upcoming “12 Years a Slave”) stars André Benjamin (a k a rapper André 3000) as Hendrix, and Hayley Atwell as Etchingham.

Etchingham was alarmed last year when Atwell told an interviewer she loved playing a working-class woman from Manchester who “swears in every line and is a chain-smoking wild child from the ’60s, who had a notoriously tempestuous relationship with Jimi.”

“Naturally I was upset about this as I am not from Manchester and come from a rather prosperous Irish family,” Etchingham said.

She said a scene shows Hendrix slamming her head with a telephone, which she said never happened.

“Later on, after he went to New York and fell in with the wrong crowd, he might have started to go off the rails, but in the early days he was a fresh, clearheaded and ambitious musician,” she said.

When she learned the movie was getting tax breaks from the Irish Film Board, Etchingham wrote to the Irish Minister for Arts complaining the board was subsidizing a film that defamed an Irish national. She also had a lawyer in LA write to Ridley, who she said was forced “to take out the defamatory bits and reshoot scenes.”

She added, “We had a lot of fun that first year in London, and I think it’s a shame that Ridley has made such a pig’s ear of the story.”

Ridley did not respond to a request for comment. His film debuted at the Toronto Film Festival.